1. Field of the Invention
The present invention relates to a program search method for a digital signal processor and, more particularly, to a program search method which can scan a program, irrespective of the presence or absence of chapter numbers indicating a specific portion of a program.
Korean Patent Application No. 93-12236 is incorporated herein by reference for all purposes.
2. Description of Related Art
In general, a digital signal processor processes signals including digital information, such as signals generated by a laser disk player (LDP), a compact disk player (CDP), a digital audio tape (DAT) recorder, a digital compact cassette (DCC) recorder, etc.
The digital signal processor can record onto a recording medium not only the digital data signal but also time information, i.e., the starting time or playing time of the program which is to be reproduced during the reproducing operation. Thus, the time information is recovered along with the digital data signal. This data signal is processed as a reproduction signal and is then output while the recovered time information can be conveyed to a user through a display such as a digitron.
Many forms of program search functions have been developed over the years. One such program search function reproduces only a part of the program content recorded on the recording medium. The partial program content is sufficient to allow the user to rapidly and precisely recognize the reproduced program. This known program search method, thus, can be performed by reproducing the corresponding program for a predetermined time, i.e., about ten to fifteen seconds measured from the reproduction starting point for each program recorded on the recording medium. This allows the user sufficient time to recognize the program being reproduced with the help of the time information.
An alternative program search function can be performed when multiple programs are recorded on the tracks of a disk and each program is separated from the previous program by a differentiating signal for differentiating the programs. These signals, which are loaded in a predetermined order on the horizontal synchronizing signal lines within a vertical blanking period, include chapter numbers, which are recorded for differentiating specific programs. When a search instruction key, e.g., an intro scan key, is operated and the differentiation signal recorded for indicating the first chapter (CH1) is detected, as shown in FIG. 1, the program is reproduced starting at the spot corresponding to the first chapter number for a predetermined time. Thereafter, the pickup is moved to the next chapter (CH2) and is used to reproduce the respective program for the predetermined time. Subsequently, the above-mentioned steps can be performed repeatedly.
For the disk type described immediately above, when a program such as a song, is stored on a laser disk along with a differentiation signal, i.e., the chapter number, which is recorded for differentiating each program, a program search function is easily performed. In contrast, when a long program such as a movie, i.e., one program, is recorded on a laser disk, since there is no need to record chapter numbers as differentiation signals for every predetermined period, chapter number search as well as other intro scan functions, cannot be performed during program reproduction. Since the differentiation of chapters by chapter numbers is impossible, it is increasingly difficult to search for the user's desired portion of a program.
An alternative program search method using a fast forward (FF) key or a rewind (REW) key is somewhat similar to the search methods already described. It will be noted that the program search method using fast forward or rewind functions requires too long a time to be of any practical use. Another form of program search method is frame detection. In this case, although frames are detected while the picture is viewed more rapidly than normal, such a program search method does not offer an appreciable advantage over the alternative program search methods described above.
Another known program search method utilizes the reproduction of a few bars beginning at the starting portion for a predetermined time so as to permit a program such as a song recorded on the disk to be recognized. However, since many songs begin with an undistinguishable prelude or introduction, this search method is insufficiently precise for recognition of a desired song. Therefore, even during a program search method utilizing the introduction of a song wherein the user optionally sets or defines a starting point for song reproduction which is offset from the starting point of a chapter, disks without chapter numbers are difficult to search for the desired song.
Additionally, in the CDP disclosed in U.S. Pat. No. 4,613,967, intermittent reproduction is performed by skipping disk tracks 50 times as fast as normal in a search mode conducted in either of the directions corresponding to the FF or REW modes of operation in order to reproduce information from nonadjacent tracks. This apparatus stores the reproduced signal temporarily and then outputs the stored signal while attenuating the reproduced signal so that the sound quality is not degraded as the program is reproduced intermittently.